Some opponents of face masks have argued that they will make people ignore other protection measures (like washing hands or distancing). A new analysis of multiple studies lays that idea to rest.

Unfounded concerns like this one can threaten public health by delaying the introduction of protective measures such as wearing of face coverings, the researchers conclude.

Burying an old theory

When face masks were first brought into the COVID-19 discussion, there were a few arguments against them. The first one is that the protection masks offer is imperfect — and while technically true, there is already convincing evidence that masks do help in preventing the disease. Another concern was that masks would make people act recklessly, giving them a sense of false security and causing a negative net effect.

This idea is sometimes called ‘risk compensation’ or ‘risk budget’, and it’s been debated for some time. Researchers have been looking at it for years, especially when it comes to introducing some kind of mandatory protection measure.

The common-cited example is the mandated wearing of bike helmets, which purportedly leads to an increase in the number of bike injuries and fatalities. Another common example is the introduction of HIV pre-exposure prophylaxis (PrEP) and HPV vaccination which allegedly leads to an increase in unprotected sex. However, none of those things are true, according to a new study.

Two quoted systematic reviews concluded:

• “In sum, this systematic review found little to no support for the hypothesis bicycle helmet use is associated with engaging in risky behaviour.”
• “The consistent, replicated evidence found across the 20 studies examined in this systematic review provides a strong body of evidence refuting that there is an association between HPV [human papillomavirus] vaccination and risky sexual behaviour”

This is why large-scale analyses are so important: individual studies can sometimes miss the big picture, and there are indeed studies suggesting that bike helmets increase the risk of accidents, but that’s not really true when you zoom out.

A team led by Professor Dame Theresa Marteau at the Behaviour and Health Research Unit from the University of Cambridge has examined the existing evidence for risk compensation. They looked at 22 systematic reviews and three observational studies, finding that both the bike and the HPV example are plain wrong. In fact, for the HPV vaccination, the opposite was found: those who were vaccinated were less likely to engage in unprotected sexual behavior.

The same thing was found in the case of face masks.

Risk compensation theory “is a dead horse that no longer needs to be beaten”

Studies on over 2,000 households suggest that wearing masks does not reduce the frequency of handwashing or hand sanitizing — another crucial hygiene measure. In fact, in two studies, self-reported rates of handwashing were higher in the groups allocated to wearing masks.

It’s an interesting and important takeaway, and a new one too because none of these initial studies were tailored to look at risk management — it’s this new analysis that pulls it all into place. According to the study’s authors, this is the final blow to the old theory of risk compensation.

“The concept of risk compensation, rather than risk compensation itself, seems the greater threat to public health through delaying potentially effective interventions that can help prevent the spread of disease,” said Professor Marteau.

“Many public health bodies are coming to the conclusion that wearing a face covering might help reduce the spread of SARS-CoV-2, and the limited evidence available suggests their use doesn’t have a negative effect on hand hygiene,” added co-author Dr. James Rubin from the Department of Psychological Medicine, King’s College London.

However, the study does have significant limitations. None of the coronavirus face mask studies had been peer-reviewed, so the findings should be taken with a grain of salt. But Martineau and colleagues say this is sufficient evidence to put risk compensation theory to rest. The theory, they say, is “a dead horse that now needs burying to try to prevent the continued threat it poses to public health, from by slowing the adoption of more effective interventions”.

The last reasonable arguments against face masks are being blown away. We’ll either follow the scientific advice, or pay the price.

Journal Reference: Mantzari, E et al. Is risk compensation threatening public health in the covid-19 pandemic? BMJ Analysis; 27 July 2020: DOI: 10.1136/bmj.m2913